The present invention relates to a driving system for a plasma display panel, and more particularly to a driving system for an X-Y matrix type plasma display panel employing an alternate current (A.C.) driving system.
In one example of an A.C.-driven X-Y type plasma display panel, a plurality of parallel, thin, linear electrodes are densely formed on a pair of insulator plates comprising of transparent glass plates or the like, respectively. The surfaces of these linear electrodes are coated with a transparent dielectric film. These respective insulator plates are placed with spacers between them in an opposed relation, with a discharge space sandwiched therebetween, so that the respective linear electrode groups may cross each other at right angles, in a matrix form. The outer periphery of the discharge space is air-tightly sealed with flint glass, and after evacuation, inert gas such as neon is filled in the space. If an A.C. voltage is applied between a pair of electrodes selected respectively from the respective groups of linear electrodes, then gas discharge occurs at the cross-point between these selected electrodes, thereby effecting a desired luminescent display.
For applying an A.C. voltage, a method is known in which a scanning voltage is applied to either the row electrode or the column electrode and a signal voltage which corresponds to a signal to be displayed, is applied to the other electrode. For instance, if the scanning voltage is sequentially applied to the successive row electrodes, data voltages corresponding to the characters are simultaneously applied to the column electrodes.
It is one object of the present invention to provide a driving system having a broad operating voltage range to be used with a plasma display panel.
Another object of the present invention is to provide a driving system for a plasma display panel, which has a high reliability but which does not generate false firings even under aging effects.
Still another object of the present invention is to provide a driving system for a plasma display panel, in which a number of driving circuits can be reduced even when there are a large number of scanning electrodes.
According to one feature of the present invention, there is a driving system for a plasma display panel, in which an independent driving voltage is fed to each driving output terminal by means of a switching circuit commonly connected, via respective diodes, to a plurality of driving output terminals. The voltage is fed when the driven output terminal to be driven is not clamped at a fixed voltage.
According to one particular feature of the present invention, a driving system provides a type of plasma display panel which is constructed so that a pair of insulator plates having linear electrodes thereon, as coated with dielectrics, are disposed in an opposed relation. In this way, the linear electrodes on the respective insulator plates may cross each other and voltages having opposite polarities are applied to the individual electrodes on the respective insulator plates. This effects a gas discharge at the cross-points between said individual electrodes. A driving circuit comprises first and second NPN transistor groups each consisting mainly of NPN transistors. The first NPN transistor group is constructed in such manner that a base of a first NPN transistor is connected to the collector of the first transistor via a resistor. The emitter and base of the first transistor are connected through a first diode with the anode side of the first diode facing to the emitter side of the first transistor. The base of the first transistor is connected to an anode side of a second diode, and the cathode side of the second diode is connected to a collector of second NPN transistor. The second NPN transistor group is constructed in such manner that the collector of the second NPN transistor is connected to cathodes of a plurality of second diodes, and the emitter of the second transistor is grounded. A driving voltage applied to the collector of the first transistor is controlled by a signal applied to the base of the second transistor in order to derive the driving voltage from the emitter of the first transistor in response to said signal.